1. Field of the Invention
The present invention relates generally to the field of medical electronics. More specifically, the present invention relates to systems for recording and graphically displaying a record of the vital signs of a patient. More particularly still, the present invention relates to a graphical recorder display system for recording and displaying a summary of one or more characteristics of a patient's vital signs.
2. Description of the Prior Art
Over the years, various medical-electronic systems have been developed which aid physicians in diagnosing and providing therapy to patients. Particularly, within the area of cardiology and heart disease, there have been significant advances. In one facet of medical electronics systems, that of monitoring vital signs of a patient, various recorders and display devices have been developed for the purpose of facilitating retention and display of vital signs, data, and for the subsequent analysis thereof.
As is well known in the medical field, records such as EKG strips are taken by a physician by sensing certain physical phenomena of the patient to provide electrical signals for recording and display on a graphical recorder. Such recorders typically advance a strip or chart of paper relative to a galvanometer pen or stylus to which electrical signals indicative of vital signs have been applied. The electrical signals then serve to control the scribing of an analog record of the said vital signs on the chart paper surface. Additional electronics may provide for periodically scribing certain trend or summary information on the chart paper to summarize the occurrence of certain events during a preceding period of time.
An example of this combined capability in a vital sign display system, in which a summary of one or more characteristics of a patient's vital signs is displayed in conjunction with an analog waveform of a basic vital sign under consideration, is seen in U.S. Pat. No. 3,893,453 entitled COMPRESSED DATA DISPLAY SYSTEM issued July 8, 1975 to Goldberg et al. and assigned to American Optical Corporation. In the aforementioned patent, the chart paper is wrapped on a cylindrical drum and the galvanometer pen generally scribes a helical base line on the surface of the cylinder's chart paper in a manner which presents the recorded display data in a compact format. An EKG waveform may be the principal vital sign information traced out on the chart paper, with events such as average heart rate and/or number of premature ventricular contractions occurring during some predetermined period being indicated by a dither mark of the pen on the chart paper for reference to a graticule or scale preprinted on the charg paper.
It is possible with a system of the type described above for the chart paper to be misaligned during its installation on the drum or recorder drive and, because the electronics responsible for timing the scribing of the dither mark is keyed, at best, to the drum or recorder drive, the dither mark may be scribed at an inaccurate position on the preprinted graticule. Further, where more than one event or parameter is to be displayed on the same graticule, it becomes important that the display marks or cursors be such as to avoid ambiguity with one another, particularly if they share a common graticule when they overlap.
Accordingly, it is a principal object of the present invention to provide an improved graphical recorder display system.
It is another object of the invention to provide an improved graphical recorder system of the type which scribes one or more cursors in a graticule on the chart. Included in this object is the provision of a system of the type described in which the scribed cursors are accurately positioned relative to the graticule.
It is a still further object to provide an improved system of the type described in which a plurality of cursors sharing a common graticule avoid ambiguity.
It is an even further object of the present invention to provide an improved graphical recorder system of the type described in which the graticule and cursor arrangement facilitates analysis of the recorded data.
It is a yet further object of the invention to provide an improved recorder system of the type described for displaying and/or summarizing vital signs, as for instance ECG display and indications of related parameters such as heart rate and arrhythmia count.